Fuel supply control system for automobile engines

ABSTRACT

A fuel supply control system for automobile engines having a fuel cutoff means provided in the carburetor to prevent a great deal of harmful exhaust gas from being discharged during the braking with the motor, and in which use is made of an auxiliary fuel supply system for correcting any delay in the recovery of fuel, in addition to the ordinary main and idle fuel supply systems provided to the carburetor, so as to ensure the automobile to shift from its coasting operation to its accelerating operation, whereby fuel may be supplied from the auxiliary fuel supply system for a predetermined time to shift the automobile from coating to fast running and thus the engine can rotate smoothly in quick response to variations in the running condition of the vehicle.

United States Patent Shimada et a].

1 51 Sept. 12, 1972 [54] FUEL SUPPLY CONTROL SYSTEM FOR AUTOMOBILEENGINES [72] Inventors: Hiroshi Shimada, Hiroshima-ken;

Mitsuru Nagai, Hiroshima-shi; Mitsuo Ohfuji, Katsuta-shi; ToshiyukiSasaki, I-litachi-shi, all of Japan [73] Assignees: Hitachi, Ltd.,Tokyo; Toyo Kogyo Company Limited, Aki-gun, Hiroshimaken, Japan [22]Filed: Oct. 2, 1969 211 Appl. No.: 863,175

[30] Foreign Application Priority Data Oct. 4, 1968 Japan ..43/71806[52] US. Cl. ..123/97 B, 123/102, 123/119, 261/DIG. 19, 261/42,261/41.4, 123/32 AB [51] Int. Cl. ..F02d 31/00, F02d 11/10 [58] Field ofSearch ..261/DIG. 19, 41, 41.4, 42; 123/119, 102, 97 B [56] ReferencesCited UNITED STATES PATENTS 2,939,444 6/1960 Leibing ..261/41.4 X2,957,463 10/ 1960 Schnabel ..261/DIG. 9 X 3,080,858 3/1963 Kane, Jr...123/102 3,372,680 3/ 1968 Scholl ..123/ 102 X 3,384,059 5/1968 Kopa..123/119 X 3,433,207 3/1969 Bassot et a1 ..123/119 3,522,794 8/ 1970Reichardt ..123/119 X 2,856,167 10/1958 Cornelius ..123/97 B 2,868,1821/1959 Cornelius ..123/97 B 2,877,998 3/1959 Cornelius ..123/97 B2,879,756 3/1959 Cornelius ..123/97 B 2,908,363 10/ 1959 Dietrich..123/97 B 2,993,485 7/1961 Cornelius ..123/97 B PrimaryExaminer-Laurence M. Goodridge Assistant Examiner-Ronald B. CoxAttorney-Craig, Antonelli & Hill [57] ABSTRACT A fuel supply controlsystem for automobile engines having a fuel cutoff means provided in thecarburetor to prevent a great deal of harmful exhaust gas from beingdischarged during the braking with the motor, and in which use is madeof an auxiliary fuel supply system for correcting any delay in therecovery of fuel, in addition to the ordinary main and idle fuel supplysystems provided to the carburetor, so as to ensure the automobile toshift from its coasting operation to its accelerating operation, wherebyfuel may be supplied from the auxiliary fuel supply system for apredetermined time to shift the automobile from coating to fast runningand thus the engine can rotate smoothly in quick response to variationsin the running condition of the vehicle.

13 Claims, 2 Drawing figures P A'TENTED E 3.690 305 SHEE'I 1 [1F 2 FIG.

INVENTORS HIAOSHI SHIMADH MITSHRU! NAGAI.

MI u OHFLAJI' and TosHIYuKI SASAKI ATTORNEY PATENTEDsEP 12 m2 SHEET 2 OF2 INVENTORS MITSMRH NAGAI, MITSuO oHI qrI HIROSH I SHIMAOA,

an TosHIYu KI SASA KI ATTORNEYS I FUEL SUPPLY CONTROL SYSTEM FORAUTOMOBILE ENGINES BACKGROUND OF THE INVENTION 1. Field of the InventionThis invention relates to a fuel supply control system for automobileengines, and more particularly to improvements in or relating to a fuelsupply control system which can prevent the unnecessary waste of a greatdeal of fuel and discharge of much harmful exhaust gas resulting from ahigh suction which develops in an intake manifold when an automobile iscoasting or running while braking with the motor.

2 Description of the Prior Art According to the prior art, the fuelsupply control system of this type has a fuel cutoff valve provided inthe idle or main fuel passage of the carburetor so that the fuel passagemay be closed by the high suction in the intake manifold to therebyinterrupt the fuel supply.

However, such a fuel supply control system resorting to fuelinterruption for the control of fuel supply causes a delay in therecovery of fuel to take place due to such factors as a differencebetween the normal fuel level of the fuel bowl and the fuel level of thefuel passage, volume and resistance of the fuel passage, etc. when thefuel supply from the idle port needs to be recovered, or moreparticularly, when the automobile shifts from a slow speed to fasterspeed or when the clutch is released to change the speed of the vehiclefrom a reduced speed. In other words, the idle fuel passage is soarranged that the intermediate part thereof extends at a level higherthan the normal fuel level of the fuel bowl, and this arrangement causesthe fuel in the fuel bowl to be equal to or lower than the normal fuellevel when the fuel passage is closed. In order that fuel may bedischarged through the idle port, the fuel passage must be filled withfuel to such a degree as to cover the quantity corresponding to theaforementioned difference in level. On the other hand, the quantity ofair introduced varies so quickly that a temporary scarcity of fuelmixture takes place to cause knocking which would greatly spoil therunning or may sometimes stop the engine.

SUMMARY OF THE INVENTION It is the primary object of the presentinvention to provide a fuel supply control system having means forcutting fuel when an automobile is coasting, and which is adapted toquickly supply fuel to the engine in response to its requirement forfuel after the speed reduction of the automobile, thereby ensuringsmooth rotation of the engine in such a reduced speed condition.

According to the present invention, the carburetor is provided not onlywith means for closing the ordinary main and idle fuel supply systems inthe reduced speed condition of an automobile, but also with an auxiliaryfuel supply system which is operated for a predetermined time after thetermination of the reduced speed condition of the automobile so as tocompensate for any delay of fuel supply which may arise from fuel cut.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a combined longitudinalsectional view and electric circuit diagram showing an example of thefuel supply control system according to the present invention; and

FIG. 2 is a similar view and diagram showing another example of the fuelsupply control system according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there isshown a carburetor 1 which includes a fuel reservoir such as a bowl 2,an air inlet passage 3, a throttle valve 4, a main fuel system 5, and anidle fuel supply system 6. The fuel bowl 2 communicates with a fuel pump8 through a fuel pipe 7. The main fuel system 5 is provided with a mainfuel passage 9 and a main nozzle 10. The idle fuel supply system 6includes an idle fuel passage 11 divided from the main fuel passage 9, ajet 12, an air bleed 13, an adjust screw 14 and an idle port 15. A fuelcutoff valve 16 is provided in the idle fuel passage 11 and this valveis opened and closed by a first solenoid 17 which is connected with abattery 20 through a change-over switch 18 and an ignition switch 19.There is also provided an auxiliary fuel supply system 21 whichcomprises an auxiliary fuel passage 23 communication the fuel bowl 2with an intake manifold 22, and an auxiliary fuel valve 24. The open endof the auxiliary fuel passage 23 is located adjacent to the inlet portof an combustion chamber. A second solenoid 25 to open and close theauxiliary fuel valve 24 is connected with the changeover switch ,18through an auxiliary switch 26, and in parallel therewith is connected acapacitor 27. A diaphragm device 28 comprising a diaphragm 29 and aspring 30 mounted therein is connected, on the one hand, with a movablecontact 31 of the change-over switch 18 through a rod shown by a dottedline, and on the other hand with the intake manifold 22 through anunnumbered pipe. The diaphragm device 28 is so arranged that the forceof the spring 30 and the suction in the intake manifold 22 are bothexerted on the lefthand side of the diaphragm 29 as viewed in FIG. 1.The change-over switch 18 consists of a fixed contact 32 connected withthe first solenoid 17, a fixed contact 33 connected with the secondsolenoid 25, and the aforementioned movable contact 31. This movablecontact 31 is adapted to engage the contact 32 when the suction in theintake manifold 22 does not exceed a level corresponding to the engineidling, and to engage the contact 33 when the said suction exceeds thesaid level. Also, the switch 26 is associated with the movable contact31 so that it is closed when the contact 31 engages the contact 32.

With the above-described arrangement of the present invention, withinthe normal range of engine operation, the movable contact 31 of thechange-over switch 18 engages the contact 32 to excite the solenoid 17to thereby open the fuel cutoff valve 16. At this time, the secondsolenoid 25 is not excited so that the auxiliary fuel valve 24 closesthe auxiliary fuel passage 23.

If the automobile reduces its speed to shift into a coasting state, thesuction in the intake manifold 22 rises to thereby move the diaphragm 29against the tension of the spring 30. Thereupon, the change-over switch18 opens its contact 31 so that the first solenoid 17 is de-energized tothereby close the fuel cutoff valve 16 and accordingly the idle fuelpassage 11. This prevents an increase in amount of harmful emition ofthe exhaust gas which would otherwise take place due to an oversupply offuel resulting from an increased suction in the intake manifold 22.

On the other hand, the movable contact 31 associated with the diaphragm29 engages the contact 33 to open the auxiliary switch 26 to therebycharge the capacitor 27.

When the automobile shifts from its coasting state into an acceleratedstate or when the clutch is released for speed change, the suction inthe intake manifold 22 falls to displace the diaphragm 29 so as toengage the movable contact 31 of the change-over switch 18 with thecontact 32 and accordingly close the auxiliary switch 26. This causesthe capacitor 27 to discharge through the second solenoid 25, which isthereby excited for a predetermined time and during that period theauxiliary fuel valve 24 is open so that fuel is supplied into the intakemanifold 22 through the aux-. iliary fuel passage 23. The open end ofthe auxiliary fuel passage 23 is located adjacent to the inlet port ofthe combustion chamber as previously mentioned, and a differential fuelpressure corresponding to the difference between the fuel level in thefuel bowl 2 and the open end of the auxiliary passage 23 has alreadyforced the fuel to reach the auxiliary fuel valve 24 by the time thatthe valve 24 is opened. Therefore, the opening of the auxiliary fuelvalve 24 causes the fuel to be quickly admitted into the combustionchamber through the intake manifold 22. While the auxiliary fuel supplysystem 21 is in operation, the suction in the intake manifold 22 acts onthe idle fuel passage 11 so that fuel may be admitted into the intakemanifold 22 in spite of the difference between the normal fuel level ofthe fuel bowl and the level of the open end of the auxiliary passage andother factors. The auxiliary fuel supply system 21 remains operativeuntil the fuel from the idle fuel supply system 6 is supplied to thecombustion chamber. In this way, smooth rotation of the engine isensured at all times when the automobile shifts from its coasting stateinto any other running condition.

FIG. 2 illustrates another embodiment of the present invention wherebythe opening time of auxiliary fuel valve 24 can be easily set to takeany value within a wider range of time. Basically, the function of thisembodiment is identical with that of the embodiment of FIG. 1.

In other words, according to the embodiment of FIG. 1, when thediaphragm 29 is actuated by the intake manifold vacuum so that themovable contact 31 of the change-over switch 18 is disengaged from thefixed contact 33, the charge beforehand stored on the capacitor 27 isdischarged into the coil of the second solenoid 25 to open the auxiliaryfuel valve 24 for a predetermined time.

On the other hand, according to another embodiment shown in FIG. 2, whenthe movable contact 31 of the change-over switch 18 is disengaged fromthe fixed contact 33, this operation is detected by a control portion 51to open the auxiliary fuel valve 24 for a predetermined time.

In other words, this control section 51 is so constructed as statedhereunder. The change-over switch 18 is identical with that shown in theembodiment of FIG. 1, and its fixed contact 33 is connected through aresistor 57 to a base of a transistor 52 in the control portion 51. Anemitter of the transistor 52 is grounded via a lead 74 and a collectorthereof is connected to the positive terminal of the battery 20 througha resistor 58 and' the ignition switch 19. Thus, the transistor 52 isturned on when the movable contact 31 and the fixed contact 33 of thechange-over switch 18 engage with each other, while it is turned offwhen these contacts are disengaged from each other. These states of thetransistor 52 are transmitted to a monostable multivibrator circuitcomprising transistors 53 and 54 through a differentiation circuitcomprising a capacitor and a resistor which are connected to thecollector of the transistor 52.

One end of the resistor 59 is connected to the collector of thetransistor 52 and also to the base of the transistor 53 in themonostable multivibrator circuit via the capacitor 60 and a diode 64,and the other end thereof is connected to ground through the lead 74.One end of a resistor 65 is connected to the junction point between thecapacitor 60 and the diode 64, and the other end is grounded through thelead 74. The emitter of the transistor 53 is grounded through the lead74 together with the emitter of the transistor 54, and the collector ofthe transistor-53 is connected to one end of a resistor 61 and to oneend of a capacitor 62. The other end of the capacitor 62 is connected toa base of the transistor 54 and also to one end of a resistor 63 whoseother end is connected together with the other end of the resistor 61 tothe positive terminal of the battery 20 through a resistor 73 and theignition switch 19.

The base of the transistor 53 is connected to a collector of thetransistor 54 through a resistor 68 and to the ground through acapacitor 67 and the lead 74. The collector of the transistor 54 isconnected to the positive terminal of the battery 20 through resistors69 and 73 and the ignition switch 19, and it is also connected to a baseof a transistor 55 via a resistor 70. The transistor 55 has its emitterconnected to the base of a transistor 56 and its collector connected tothe collector of the transistor 56. The transistor 56 has its emitterconnected to the ground through the lead 74 and its collector connectedto the positive terminal of the battery 20 through the coil of thesecond solenoid 25 for actuating the auxiliary fuel valve 24 and theignition switch 19.

On the other hand, a parallel connection of a Zener diode 71 and acapacitor 72 forms a kind of voltage regulator circuit. The Zener diode71 has its cathode side connected to the junction point between theresistors 69 and 73 and its anode side connected to ground through thelead 74 to thereby maintain a source voltage supplied to the controlsection 51 at a constant value.

With the construction described above, the control section 51 operatesin the following manner.

When the intake manifold vacuum causes the movable contact 31 of thechange-over switch 18 to engage with the fixed contact 32, the fixedcontact 33 is left open and thus there is no current flowing into thebase of the transistor 52 so that the transistor 52 remainsnonconductive.

At this time, the capacitor 60 is charged to have positive polarity onits electrode on the side of the collector of the transistor 52 andnegative polarity on its electrode on the other side. There is nocurrent flowing through the 'resistor 65, and there is no change in thestate of the succeeding circuitry, thereby maintaining a steady state.The resistors 61, 63, 66, 68 and 69 are designed to have such valuesthat, in the steady state of the monostable multivibrator circuitcomprising the transistors 53 and 54, the transistor 53 is nonconductingand the transistor 54 is conducting. In this state the capacitor 62 ischarged to have positive polarity on its electrode on the side of thecollector of the transistor 53 and negative polarity on the side of thebase of the transistor 54. The monostable multivibrator circuit is sodesigned that when a positive voltage is applied to the base of thetransistor 53, the transistors 53 and 54 are caused to change theirrespective states to remain in the changed states until the capacitor 62completely discharges its stored charge.

Thus, in the steady state of the monostable multivibrator circuit thetransistor 54 is conducting, and the potential of the collector of thetransistor 54 is substantially zero so that the transistors 55 and 56are rendered nonconductive, because no base currents flow into theirbases. In this state, there is no current flowing through the coil ofthe second solenoid 25 for actuating the auxiliary fuel valve 24, andhence the auxiliary fuel valve 24 remains closed.

Under these conditions, if the engine is decelerated, the intakemanifold vacuum goes higher to retract the diaphragm 29 so that themovable contact 31 is disengaged from the fixed contact 32 and engageswith the fixed contact 33, thereby supplying a base current to thetransistor 52 to turn it conductive. When this happens, the chargebeforehand stored in the capacitor 60 will be discharged through thetransistor 52 and the resistor 65. In this case, however, a negativevoltage is applied to the anode of diode 64 so that no change takesplace in the monostable multivibrator circuit and thereafter, therebymaintaining the same state.

Then, upon changing of the operating state of the engine fromdeceleration to acceleration, the intake manifold vacuum is lowered toswitch the movable contact 31 of the change-over switch 18 from the sideof the fixed contact 33 to the side of the fixed contact 32.

This causes the conducting transistor 52 to become nonconductive and thepotential of the collector of the transistor 52 rises to thereby supplya charging current to the capacitor 60 and to apply a positive voltageto the base of the transistor 53. Consequently, the transistor 53becomes conductive and the charge beforehand charged in the capacitor 62is discharged to apply a reverse bias between the base and emitter ofthe transistor 54 so that the transistor 54 is maintained nonconductiveuntil the capacitor 62 finishes discharging. This in turn results in arise in the potential of the collector of the transistor 54 so that thetransistors 55 and 56 are rendered conductive and a current flows intothe coil of the second solendoid 25 from the positive terminal of thebattery 20 through the transistor 56, thereby opening the auxiliary fuelvalve 24 to directly supply fuel into the intake manifold. In this way,a delay in fuel supply which tends to occur during a great accelerationcan be eliminated to improve engine performance.

If an arrangement is made so that the fuel of the auxiliary fuel supplysystem is introduced directly from the fuel pump 8, instead of throughthe fuel bowl 2, then the higher pressure provided by the pump 8 willenable the fuel to be admitted into the intake pipe 22 more rapidly andmore finely when the auxiliary fuel valve 24 is opened, and this willsubstantially eliminate any delayed supply of fuel to the intakemanifold 22.

Also, the means for operating the auxiliary fuel valve 24 may be anyother suitable means than that shown and described with respect to theforegoing embodiments.

We claim:

1. In an automobile engine comprising a carburetor having an air inletpassage, a throttle valve disposed in said air inlet passage, a fuelbowl and a fuel passage through which said fuel bowl communicates withsaid air inlet passage; and an intake manifold coupled to saidcarburetor; a fuel supply control system for the automobile enginecomprising: an auxiliary fuel passage interconnecting said fuel bowl andsaid intake manifold, a first electromagnetic. valve disposed in saidfuel passage, a second electromagnetic valve disposed in said auxiliaryfuel passage, a first solenoid of said first electromagnetic valve beingconnected to a power source through a change-over switch coupled tomeans for detecting a decelerating state of said engine so that saidfirst solenoid is denergized upon deceleration of said engine to causesaid first electromagnetic valve to close said fuel passage, a secondsolenoid of said second electromagnetic valve being connected to saidpower source through said change-over switch coupled to said means fordetecting a decelerating state of said engine, switching means and timermeans which is associated with said change-over switch and saidswitching means so that said second solenoid of said secondelectromagnetic valve is energized upon termination of said deceleratingstate of said engine for a period of time determined by said timer meansto cause said second solenoid valve to open said auxiliary fuel passage,wherein said timer means comprises a monostable multivibrator connectedin parallel with said power source through said change-over switch withrespect to said second solenoid.

2. A fuel supply control system for an internal combustion enginecomprising:

a carburetor having an air inlet passage,

a throttle valve disposed in said air inlet passage,

a fuel reservoir,

a first fuel passage providing fuel communication between said reservoirand said air inlet passage, and

an intake manifold coupled to said carburetor, said fuel supply controlsystem comprising:

a second fuel passage, in addition to said first fuel passage, forproviding fuel communication between said reservoir and said intakemanifold;

first valve means, disposed in said first passage, for controlling thequantity of fuel flowing from said reservoir to said air inlet passage;

second valve means, disposed in said second fuel passage for controllingthe quantity of fuel flowing from said reservoir into said intakemanifold; and

means for effecting the closure of said first fuel passage by said firstvalve means in response to the commencement of deceleration of saidengine and for effecting the opening of said second valve means for apredetermined period of time in response to thetermination ofdeceleration of said engine,

said effecting means comprises means, switchably connectable with eachof said first and second valve means, for supplying first and secondcontrol signals thereto for effecting the opening and clos ing thereofandmeans, responsive to the pressure in said intake manifold, foreffecting the supplying of said control signals to said first and secondvalve means by said first switch means, in accordance with thedeceleration condition of said engine, and said control signal supplyingmeans comprises a source of electric power, a first switch means, havingan input terminal and first and second output terminals, coupled to saidsource of electric power at the input terminals thereof, for supplyingsaid first control signal tosaid first valve means at the first outputterminal thereof and said second control signal to said second valvemeans at the second output terminal thereof, the application of saidcontrol signals to said first and second valve means from said outputterminals being effected by said pressure-responsive means and means,coupled to said second output terminal of said first switch means andsaid second valve means, for maintaining the application of said secondcontrol signal to said second valve means for said predetermined periodof time, I said maintaining means comprises a storage circuit coupled tosaid second output terminal and switchably coupled to said second valvemeans, for generating said second control signal upon the termination ofdeceleration of said engine, said storage means comprising a capacitorconnected between said'second output terminal and a source of referencepotential, whereby the delay in the supplying of fuel from said fuelsupply subsequent to the deceleration of the engine is compensated so asto maintain the airfuel mixture ratio at a suitable level. 3. A fuelsupply control system for an internal combustion engine comprising:

a carburetor having an air inlet passage,

a throttle valve disposed in said air inlet passage,

a fuel reservoir,

a first fuel passage providing fuel communication between said reservoirand said air inlet passage, and

an intake manifold coupled to said carburetor, said fuel supply controlsystem comprising:

a second fuel passage, in addition to said first fuel passage, forproviding fuel communication between said reservoir and said intakemanifold;

first valve means, disposed in said first fuel passage, for controllingthe quantity of fuel flowing from said reservoir to said air inletpassage;

second valve means, disposed in said second fuel passage for controllingthe quantity of fuel flowing from said reservoir into said intakemanifold; and

means for effecting the closure of said first fuel passage by said firstvalve means in response to the commencement of deceleration of saidengine and for effecting the opening of said second valve means for apredetermined period of time in response to the termination ofdeceleration of said engine,

said effecting means comprises means, switchably connectable with eachof'said first and second valve means, for supplying first and secondcontrol signals thereto for effecting the opening and closing thereofand means, responsive to the pressure I in said intake manifold, foreffecting the supplying of said control signals tosaid first and secondvalve means by said first switch means, in' accordance with thedeceleration condition of said engine, and said control signal supplyingmeans comprises a source of electric power, a first switch means, havingan input terminal and first and second output terminals, coupled to saidsource of electric power at the input terminals thereof, for supplyingsaid first control signal to said first valve means at the first outputterminal thereof, and said second control signal to said second, valvemeans at the second output terminal thereof, the application of saidcontrol signalsto said first and second valve means from said outputterminals being effected by said pressure-responsive means and meanscoupled to said second output terminal of said first switch means andsaid second valve means, for

maintaining the application of said second control signal to said secondvalve means for said predetermined period of time,

said maintainingmeans comprises a storage circuit coupled to said secondoutput terminal and switchably coupled to said second valve means, forgenerating said second control signal upon the termination ofdeceleration of said engine, said storage means including a timingcircuit connected between said second output terminal and said secondvalve means and including a capacitorconnected between said secondoutput terminal and a source of reference potential,

whereby the delay in the supplying of fuel from said fuel supplysubsequent to the deceleration of the engine is compensated so as tomaintain the airfuel mixture ratio at a suitable level.

4. A fuel supply control system for an internal combustion enginecomprising:

a carburetor having an air inlet passage,

a throttle valve disposed in said air inlet passage,

a fuel reservoir,

a first fuel reservoir,

a first fuel passage providing fuel communication between said reservoirand said air inlet passage, nd

an intake manifold coupled to said carburetor, said fuel supply controlsystem comprising:

a second fuel passage, in addition to said first fuel passage, forproviding fuel communication between said reservoir and said intakemanifold;

first valve means, disposed in said first fuel passage, for controllingthe quantity of fuel flowing from said reservoir to said air inletpassage; second valve means, disposed in said second fuel passage, forcontrolling the quantity of fuel flowing from said reservoir into saidintake manifold; and

means for effecting the closure of said first fuel passage by said firstvalve means in response to the commencement of deceleration of saidengine and for effecting the opening of said second valve means for apredetermined period of time in response to the termination ofdeceleration of said engine,

said effecting means comprises means, switchably connectable with eachof said first and second valve means, for supplying first and secondcontrol signals thereto for effecting the opening and closing thereofand means, responsive to the pressure in said intake manifold, foreffecting the supplying of said control signals to said first and secondvalve means by said first switch means, in accordance with thedeceleration condition of said engine, and

said control signal supplying means comprises a source of electricpower, a first switch means, having an input terminal and first andsecond output terminals, coupled to said source of electric power at theinput terminals thereof, for supplying said first control signal to saidfirst valve means at the first output terminal thereof and said secondcontrol signal to said second valve means at the second output terminalthereof, the application of said control signals to said first andsecond valve means from said output terminals being effected by saidpressure responsive means and means, coupled to said second outputterminal of said first switch means and said second valve means, formaintaining the application of said second control signal to saidsecondvalve means for said predetermined period of time,

said maintaining means comprises a storage circuit coupled to saidsecond output terminal and switchably coupled to said second valvemeans, for generating said second control signal upon the termination ofdeceleration of said engine, said storage means including a timingcircuit comprising a monostable multivibrator switchably coupled betweenthe second output terminal of said first switch means and second valvemeans,

whereby the delay supplying of fuel from said fuel supply subsequent tothe deceleration of the engine is compensated so as to maintain theair-fuel mixture ratio at a suitable level.

5. In a automobile engine comprising a carburetor having an air inletpassage, a throttle valve disposed in said air inlet passage, a fuelbowl and a fuel passage through which said fuel bowl communicates withsaid air inlet passage; and an intake manifold coupled to saidcarburetor; a fuel supply control system for the automobile enginecomprising: an auxiliary fuel passage interconnecting said fuel bowl andsaid intake manifold, a first electromagnetic valve disposed in saidfuel passage, a second electromagnetic valve disposed in said auxiliaryfuel passage, a first solenoid of said first electromagnetic valve beingconnected to a power ource through a ch ge;over switch coupled to me nsor detecting a dece eratmg state of said engine so t at said firstsolenoid is deenergized upon deceleration of said engine to cause saidfirst electromagnetic valve to close said fuel passage, a secondsolenoid of said second electromagnetic valve being connected to saidpower source through said change-over switch coupled to said means fordetecting a decelerating state of said engine, switching means and timermeans which is associated with said change-over switch and saidswitching means so that said second solenoid of said secondelectromagnetic valve is energized upon termination of said deceleratingstate of said engine for a period of time determined by said timer meansto cause said second solenoid valve to open said auxiliary fuel passage,wherein said timer means comprises a capacitor connected in parallelwith said power source through said change-over switch with respect tosaid second solenoid.

6. A system according to claim 2, wherein each of said first and secondvalve means comprises means, responsive to the application of electricalsignals thereto, for opening and closing said fuel passages.

7. A system according to claim 6, wherein said valve means compriseselectro-magnetic valve means, the solenoid of said first valve meansbeing connected to said first output terminal of said first switch meansand the solenoid of said second valve means being connected to saidmaintaining means.

8. A system according to claim 4, wherein said timing circuit furtherincludes a first transistor switching circuit connected between saidmonostable multivibrator and said second output terminal and an outputdriving circuit for supplying the output of said monostablemultivibrator to said second valve means.

9. A system according to claim 8, wherein said timing circuit furtherincludes a capacitor connecting said first transistor switching circuitto said monostable multivibrator.

10. A system according to claim 9, wherein said valve means compriseelectro-magnetic valve means, the solenoid of said first valve meansbeing connected to the first output terminal of said first switch meansand the solenoid of said second valve means being connected to saidoutput driving circuit.

11. A system according to claim 10, wherein said timing circuit furtherincludes a voltage regulator circuit connected between said source ofelectric power and said reference potential.

12. A system according to claim 11, further including a switch connectedbetween said source of electric power and the input terminal ofsaidfirst switch means.

13. A system according to claim 3, wherein said timing circuit furtherincludes a switch connected between said second terminal of said switchmeans and said second valve means, said switch being responsive to saidpressure responsive means.

1. In an automobile engine comprising a carburetor having an air inletpassage, a throttle valve disposed in said air inlet passage, a fuelbowl and a fuel passage through which said fuel bowl communicates withsaid air inlet passage; and an intake manifold coupled to saidcarburetor; a fuel supply control system for the automobile enginecomprising: an auxiliary fuel passage interconnecting said fuel bowl andsaid intake manifold, a first electromagnetic valve disposed in saidfuel passage, a second electromagnetic valve disposed in said auxiliaryfuel passage, a first solenoid of said first electromagnetic valve beingconnected to a power source through a change-over switch coupled tomeans for detecting a decelerating state of said engine so that saidfirst solenoid is denergized upon deceleration of said engine to causesaid first electromagnetic valve to close said fuel passage, a secondsolenoid of said second electromagnetic valve being connected to saidpower source through said changeover switch coupled to said means fordetecting a decelerating state of sAid engine, switching means and timermeans which is associated with said change-over switch and saidswitching means so that said second solenoid of said secondelectromagnetic valve is energized upon termination of said deceleratingstate of said engine for a period of time determined by said timer meansto cause said second solenoid valve to open said auxiliary fuel passage,wherein said timer means comprises a monostable multivibrator connectedin parallel with said power source through said change-over switch withrespect to said second solenoid.
 2. A fuel supply control system for aninternal combustion engine comprising: a carburetor having an air inletpassage, a throttle valve disposed in said air inlet passage, a fuelreservoir, a first fuel passage providing fuel communication betweensaid reservoir and said air inlet passage, and an intake manifoldcoupled to said carburetor, said fuel supply control system comprising:a second fuel passage, in addition to said first fuel passage, forproviding fuel communication between said reservoir and said intakemanifold; first valve means, disposed in said first passage, forcontrolling the quantity of fuel flowing from said reservoir to said airinlet passage; second valve means, disposed in said second fuel passagefor controlling the quantity of fuel flowing from said reservoir intosaid intake manifold; and means for effecting the closure of said firstfuel passage by said first valve means in response to the commencementof deceleration of said engine and for effecting the opening of saidsecond valve means for a predetermined period of time in response to thetermination of deceleration of said engine, said effecting meanscomprises means, switchably connectable with each of said first andsecond valve means, for supplying first and second control signalsthereto for effecting the opening and closing thereof and means,responsive to the pressure in said intake manifold, for effecting thesupplying of said control signals to said first and second valve meansby said first switch means, in accordance with the decelerationcondition of said engine, and said control signal supplying meanscomprises a source of electric power, a first switch means, having aninput terminal and first and second output terminals, coupled to saidsource of electric power at the input terminals thereof, for supplyingsaid first control signal to said first valve means at the first outputterminal thereof and said second control signal to said second valvemeans at the second output terminal thereof, the application of saidcontrol signals to said first and second valve means from said outputterminals being effected by said pressure-responsive means and means,coupled to said second output terminal of said first switch means andsaid second valve means, for maintaining the application of said secondcontrol signal to said second valve means for said predetermined periodof time, said maintaining means comprises a storage circuit coupled tosaid second output terminal and switchably coupled to said second valvemeans, for generating said second control signal upon the termination ofdeceleration of said engine, said storage means comprising a capacitorconnected between said second output terminal and a source of referencepotential, whereby the delay in the supplying of fuel from said fuelsupply subsequent to the deceleration of the engine is compensated so asto maintain the air-fuel mixture ratio at a suitable level.
 3. A fuelsupply control system for an internal combustion engine comprising: acarburetor having an air inlet passage, a throttle valve disposed insaid air inlet passage, a fuel reservoir, a first fuel passage providingfuel communication between said reservoir and said air inlet passage,and an intake manifold coupled to said carburetor, said fuel supplycontrol system comprising: a second fuel passage, in addition tO saidfirst fuel passage, for providing fuel communication between saidreservoir and said intake manifold; first valve means, disposed in saidfirst fuel passage, for controlling the quantity of fuel flowing fromsaid reservoir to said air inlet passage; second valve means, disposedin said second fuel passage for controlling the quantity of fuel flowingfrom said reservoir into said intake manifold; and means for effectingthe closure of said first fuel passage by said first valve means inresponse to the commencement of deceleration of said engine and foreffecting the opening of said second valve means for a predeterminedperiod of time in response to the termination of deceleration of saidengine, said effecting means comprises means, switchably connectablewith each of said first and second valve means, for supplying first andsecond control signals thereto for effecting the opening and closingthereof and means, responsive to the pressure in said intake manifold,for effecting the supplying of said control signals to said first andsecond valve means by said first switch means, in accordance with thedeceleration condition of said engine, and said control signal supplyingmeans comprises a source of electric power, a first switch means, havingan input terminal and first and second output terminals, coupled to saidsource of electric power at the input terminals thereof, for supplyingsaid first control signal to said first valve means at the first outputterminal thereof and said second control signal to said second valvemeans at the second output terminal thereof, the application of saidcontrol signals to said first and second valve means from said outputterminals being effected by said pressure-responsive means and meanscoupled to said second output terminal of said first switch means andsaid second valve means, for maintaining the application of said secondcontrol signal to said second valve means for said predetermined periodof time, said maintaining means comprises a storage circuit coupled tosaid second output terminal and switchably coupled to said second valvemeans, for generating said second control signal upon the termination ofdeceleration of said engine, said storage means including a timingcircuit connected between said second output terminal and said secondvalve means and including a capacitor connected between said secondoutput terminal and a source of reference potential, whereby the delayin the supplying of fuel from said fuel supply subsequent to thedeceleration of the engine is compensated so as to maintain the air-fuelmixture ratio at a suitable level.
 4. A fuel supply control system foran internal combustion engine comprising: a carburetor having an airinlet passage, a throttle valve disposed in said air inlet passage, afuel reservoir, a first fuel reservoir, a first fuel passage providingfuel communication between said reservoir and said air inlet passage,and an intake manifold coupled to said carburetor, said fuel supplycontrol system comprising: a second fuel passage, in addition to saidfirst fuel passage, for providing fuel communication between saidreservoir and said intake manifold; first valve means, disposed in saidfirst fuel passage, for controlling the quantity of fuel flowing fromsaid reservoir to said air inlet passage; second valve means, disposedin said second fuel passage, for controlling the quantity of fuelflowing from said reservoir into said intake manifold; and means foreffecting the closure of said first fuel passage by said first valvemeans in response to the commencement of deceleration of said engine andfor effecting the opening of said second valve means for a predeterminedperiod of time in response to the termination of deceleration of saidengine, said effecting means comprises means, switchably connectablewith each of said first and second valve means, for supplying first andsecond controL signals thereto for effecting the opening and closingthereof and means, responsive to the pressure in said intake manifold,for effecting the supplying of said control signals to said first andsecond valve means by said first switch means, in accordance with thedeceleration condition of said engine, and said control signal supplyingmeans comprises a source of electric power, a first switch means, havingan input terminal and first and second output terminals, coupled to saidsource of electric power at the input terminals thereof, for supplyingsaid first control signal to said first valve means at the first outputterminal thereof and said second control signal to said second valvemeans at the second output terminal thereof, the application of saidcontrol signals to said first and second valve means from said outputterminals being effected by said pressure responsive means and means,coupled to said second output terminal of said first switch means andsaid second valve means, for maintaining the application of said secondcontrol signal to said second valve means for said predetermined periodof time, said maintaining means comprises a storage circuit coupled tosaid second output terminal and switchably coupled to said second valvemeans, for generating said second control signal upon the termination ofdeceleration of said engine, said storage means including a timingcircuit comprising a monostable multivibrator switchably coupled betweenthe second output terminal of said first switch means and second valvemeans, whereby the delay supplying of fuel from said fuel supplysubsequent to the deceleration of the engine is compensated so as tomaintain the air-fuel mixture ratio at a suitable level.
 5. In aautomobile engine comprising a carburetor having an air inlet passage, athrottle valve disposed in said air inlet passage, a fuel bowl and afuel passage through which said fuel bowl communicates with said airinlet passage; and an intake manifold coupled to said carburetor; a fuelsupply control system for the automobile engine comprising: an auxiliaryfuel passage interconnecting said fuel bowl and said intake manifold, afirst electromagnetic valve disposed in said fuel passage, a secondelectromagnetic valve disposed in said auxiliary fuel passage, a firstsolenoid of said first electromagnetic valve being connected to a powersource through a change-over switch coupled to means for detecting adecelerating state of said engine so that said first solenoid isdeenergized upon deceleration of said engine to cause said firstelectromagnetic valve to close said fuel passage, a second solenoid ofsaid second electromagnetic valve being connected to said power sourcethrough said change-over switch coupled to said means for detecting adecelerating state of said engine, switching means and timer means whichis associated with said change-over switch and said switching means sothat said second solenoid of said second electromagnetic valve isenergized upon termination of said decelerating state of said engine fora period of time determined by said timer means to cause said secondsolenoid valve to open said auxiliary fuel passage, wherein said timermeans comprises a capacitor connected in parallel with said power sourcethrough said change-over switch with respect to said second solenoid. 6.A system according to claim 2, wherein each of said first and secondvalve means comprises means, responsive to the application of electricalsignals thereto, for opening and closing said fuel passages.
 7. A systemaccording to claim 6, wherein said valve means compriseselectro-magnetic valve means, the solenoid of said first valve meansbeing connected to said first output terminal of said first switch meansand the solenoid of said second valve means being connected to saidmaintaining means.
 8. A system according to claim 4, wherein said timingcircuit further includes a first transistor switching circuit connectedbetween said monostable multivibratOr and said second output terminaland an output driving circuit for supplying the output of saidmonostable multivibrator to said second valve means.
 9. A systemaccording to claim 8, wherein said timing circuit further includes acapacitor connecting said first transistor switching circuit to saidmonostable multivibrator.
 10. A system according to claim 9, whereinsaid valve means comprise electro-magnetic valve means, the solenoid ofsaid first valve means being connected to the first output terminal ofsaid first switch means and the solenoid of said second valve meansbeing connected to said output driving circuit.
 11. A system accordingto claim 10, wherein said timing circuit further includes a voltageregulator circuit connected between said source of electric power andsaid reference potential.
 12. A system according to claim 11, furtherincluding a switch connected between said source of electric power andthe input terminal of said first switch means.
 13. A system according toclaim 3, wherein said timing circuit further includes a switch connectedbetween said second terminal of said switch means and said second valvemeans, said switch being responsive to said pressure responsive means.